B737-400 suffers loss of pressurization during later stages of descent for landing.

Attributes
ACN	757519
Time
Date	200710
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zzz.tracon
State Reference	CA
Altitude	msl single value : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : zzz.tracon
Operator	common carrier : air carrier
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Flight Phase	descent : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 240 flight time type : 5500
ASRS Report	757519
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 240 flight time type : 12500
ASRS Report	757521
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : cabin alt warning horn
Resolutory Action	aircraft : equipment problem dissipated flight crew : exited adverse environment
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance Environmental Factor
Primary Problem	Aircraft

Narrative:

On descent into ZZZ passing through 11000 ft 1 mi northwest of albas we got the cabin altitude warning horn. We immediately donned our oxygen masks and established crew communications. Once we were able to silence the horn; we took out the checklist; noting we were now below 10000 ft. ATC then assigned us a new heading; altitude of 3000 ft; and a new frequency. We began to run the 'automatic fail unscheduled pressurization change' checklist in the abnormal section of the QRH. We got down to the 'pressurization mode selector -- standby;' and by this time we were already down to about 4000 ft and were on a tight downwind for ZZZ. We decided to terminate the checklist and land. We did not declare an emergency or ask for assistance from ATC due to the fact we were already on the approach and descending at a slow rate; so passenger comfort was not an issue.

Original NASA ASRS Text

Title: B737-400 SUFFERS LOSS OF PRESSURIZATION DURING LATER STAGES OF DESCENT FOR LNDG.

Narrative: ON DSCNT INTO ZZZ PASSING THROUGH 11000 FT 1 MI NW OF ALBAS WE GOT THE CABIN ALT WARNING HORN. WE IMMEDIATELY DONNED OUR OXYGEN MASKS AND ESTABLISHED CREW COMS. ONCE WE WERE ABLE TO SILENCE THE HORN; WE TOOK OUT THE CHKLIST; NOTING WE WERE NOW BELOW 10000 FT. ATC THEN ASSIGNED US A NEW HDG; ALT OF 3000 FT; AND A NEW FREQ. WE BEGAN TO RUN THE 'AUTO FAIL UNSCHEDULED PRESSURIZATION CHANGE' CHKLIST IN THE ABNORMAL SECTION OF THE QRH. WE GOT DOWN TO THE 'PRESSURIZATION MODE SELECTOR -- STANDBY;' AND BY THIS TIME WE WERE ALREADY DOWN TO ABOUT 4000 FT AND WERE ON A TIGHT DOWNWIND FOR ZZZ. WE DECIDED TO TERMINATE THE CHKLIST AND LAND. WE DID NOT DECLARE AN EMER OR ASK FOR ASSISTANCE FROM ATC DUE TO THE FACT WE WERE ALREADY ON THE APCH AND DSNDING AT A SLOW RATE; SO PAX COMFORT WAS NOT AN ISSUE.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.